In the process of extracting hydrocarbons, e.g., petroleum, from beneath the surface of the earth, wells are drilled and steel pipe (casing) is placed into the drilled hole (wellbore or borehole). Cement is then pumped into the annular space between the casing and the rock wall of the borehole (formation). The cement serves two major purposes. First, it transfers stress from the casing to the formation, increasing the effective strength and working pressure of the casing. Second, it serves to isolate vertically adjacent zones within the formation, preventing migration of liquids and gases up the wellbore between the formation and the casing, from one zone to the next. Accordingly, it is important to assure the quality of the cement both during completion of the well and during its producing life. Acoustic cement evaluation devices (cement bond logs, or CBL) conveyed by a cable (wireline) to move the tools up and down in the borehole have been the primary device to provide this assurance. The principle of evaluation is based on the loss of energy over time or distance of an acoustic wave excited in the casing. One area of conventional focus has been on determining whether cement is present outside the casing, e.g., to determine whether only fluid is present between the casing and the formation (free pipe), whether the space between the casing and the formation is filled with cement bonded to the casing (fully cemented pipe), or whether a small gap, filled with fluid, exists between the cement and casing (micro-annulus). However, conventional techniques are unable to adequately evaluate properties of the cement, such as properties indicative of the strength of the cement.